1. Field of the Invention
The present invention relates to a device interconnect system in which an information exchange method between a plurality of devices interconnected via an analog signal line is improved.
2. Discussion of the Background
Nowadays, video programs are supplied using analog media (VHS video, laser disk, ground broadcast, and the like) or digital media (DVD video, satellite broadcast, and the like) in a standard TV system (NTSC or the like). In a high-resolution TV system (HDTV), video programs are supplied using analog media (MUSE Hi-Vision satellite broadcast or the like). A digital HDTV system (for home use) has entered a practical stage.
When a video program signal is sent from a given device to another device, even when original source contents are digitally recorded, an analog line (composite or component) is currently used more prevalently than a digital line. In the future, a digital line will become the mainstream, but an analog line is projected to be used prevalently for home use for the time being.
Video devices are interconnected via an analog line, and various kinds of information (control command, service information, video ID, and the like) can be superposed on the vertical blanking interval (VBI) of a video signal (analog video signal) that flows in the analog line, thus improving user""s convenience. However, when the contents of compatible VBI information differ in units of devices connected, the length and contents of information to be superposed on the VBI must be changed as needed.
The present invention has been made in consideration of the above situation, and has as its object to provide a device interconnect system which can transfer information of various contents and lengths that can be changed in correspondence with a connection partner using a video blanking interval (vertical blanking interval VBI) between devices which are interconnected via an analog video signal line.
In order to achieve the above object, in a device interconnect system according to the present invention, which transfers an analog video signal containing predetermined information (command information, additional information, video ID information, and the like) in a vertical blanking interval (VBI) between a plurality of devices (an STB with an HY terminal, VCR with an HY terminal, or the like serving as a master device/source device, and a VCR with an HY terminal, a TV with an HY terminal, or the like serving as a slave device/sink device) via an analog line, information (bits 1 to 20) having a word configuration (words 0 to 2+CRCC in FIG. 20) defined by a predetermined number of bits (variable within the range from 5 bits to 80 bits) is superposed in a predetermined period (e.g., 49.1 xcexcs) of a predetermined line (line number 10 in FIG. 20 or L10 in FIG. 31) in the vertical blanking interval (VBI) at a predetermined clock (fsc/32 to fsc/2).
The predetermined clock (fsc/32 to fsc/2) is obtained by frequency-dividing (by xc2xd to {fraction (1/32)}) a color subcarrier frequency (fsc; about 3.58 MHz in NTSC) of an analog video signal which is transferred from a transmitting device (master device/source device) of the plurality of devices to a receiving device (slave device/sink device) of the plurality of devices or an upper limit frequency (fmax; about 3 MHz in home-use VHS video) of a luminance component (Y signal component) of the analog video signal. The predetermined number of bits (5 bits to 80 bits) of the information (bits 1 to 20) superposed on the predetermined line (line number 10 in FIG. 20) of the vertical blanking interval (VBI) can be changed in correspondence with a frequency-division ratio (xc2xd TO {fraction (1/32)}) with respect to the color subcarrier frequency (fsc) or the upper limit frequency (fmax) of the luminance component.
The frequency-division ratio (xc2xd to {fraction (1/32)}) can be changed in correspondence with contents (contents of command information, additional information, and the like) of the predetermined information which is transferred from the transmitting device (master device/source device) to the receiving device (slave device/sink device).
The predetermined information (command information, additional information, and the like) can be packetized in a predetermined format (FIG. 23). In this case, the frequency-division ratio (xc2xd to {fraction (1/32)}) can be changed in correspondence with contents of the packet (contents of each layer level).
The vertical blanking interval (VBI) can contain text information (teletext/closed caption in FIG. 19). In this case, the frequency-division ratio (xc2xd to {fraction (1/32)}) can be changed in correspondence with a partner (a text decoder (not shown) or the like) to which the text information is sent.
In a device interconnect system according to the present invention, the predetermined information (command information and the like) is exchanged in a packet format (FIG. 23) consisting of a plurality of layer levels between a plurality of devices (an STB with an HY terminal, VCR with an HY terminal, or the like serving as a master device/source device or via an analog line, and a VCR with an HY terminal, a TV with an HY terminal, or the like serving as a slave device/sink device). Information used to confirm a type of a transmitting device (master device/source device) of the plurality of devices or a receiving device (slave device/sink device) of the plurality of devices is stored in a predetermined layer (layer level 4) of the packet format, and information depending on the type (type dependent field) is stored in a layer (layer level 5) lower than the predetermined layer (layer level 4) of the packet format.
In a device interconnect system according to the present invention, an information pack (synchronization+payload+CRCC) having a predetermined word configuration (REF+words 0 to 2+CRCC in FIG. 20) is superposed on a predetermined line (L10 in FIG. 31) in the vertical blanking interval (VBI), and an information packet containing a packet header, a type code, and a type dependent field is formed by a set of one or more information packs (synchronization+payload+CRCC).
Note that the packet header (FIG. 31) of the information packet can contain version number information, packet size information, and command/response identification information used to identify a command and a response to the command.
The predetermined information (command information and the like) can be exchanged in a packet format (FIG. 23, FIG. 31) consisting of a plurality of layer levels between the transmitting device (master device/source device) and receiving device (slave device/sink device), and the version number information, the packet size information, the command/response identification information, the type code, and the type dependent field can belong to different layer levels of the plurality of layer levels.
The information packet (packet header+type code+type dependent field in FIG. 31) can have a common format (layer levels 1 to 5 in FIG. 23), and various kinds of information (various existing commands, newly expanded commands, and the like) can be exchanged using the common format between the transmitting device (master device/source device) and receiving device (slave device/sink device).
The predetermined information (command information and the like) can be exchanged in a packet format (FIG. 23) consisting of a plurality of layer levels between the transmitting device (master device/source device) and receiving device (slave device/sink device); the version number information can belong to a layer level different from the packet size information, the command/response identification information, the type code, and the type dependent field of the plurality of layer levels; and contents or the number of layer levels of the plurality of layer levels can be changed in accordance with the version number information (layer level 1 in FIG. 23).
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.